Bonding member



July 24, 1962 J. w. DENlsoN, JR 3,045,332

BONDING MEMBER Filed Jan. 28, 1955 INVENTOR'- JAMES W. DENISON,JR.

BYw m ATTO 'i NEY.

Unite States 3,@4532 Patented July 24, 1962 3,045,332 BoNDrNo MEMBERJames W. Denison, Jr., Owensboro, Ky., assigner to General ElectricCompany, a corporation of New York Filed Jan. Z8, 1955, Ser. No. 484,780Claims. (Cl. 29182.5)

" Igether. Usually, gas burners are used to provide the heat necessaryto effect the bonds. However, from the standpoints of efficiency, thedegree of control possible and for various other reasons it is moredesirable to employ electrical heating means instead of gas burners.Heretofore, electrical heating has been utilized in effecting bonds byassembling between members to be bonded a metallic member which whensubjected to a suiiiciently strong R.F. iield would heat up causing themembers to fuse and thereby provide a bond. However, often it is thecase that the members to be joined are formed of materials having suchexpansion characteristics as to make it diicult to provide a metalbonding member that will satisfactorily match the members yto be bonded.Accordingly, a primary object of my invention is to provide a new andimproved means for eifecting a bond by means of electrical heating.

Another object of my invention is to provide new and improved means forproviding a bond which is adapted for satisfactorily bonding members ofdiiferent expansion characteristics. t

Another object of my invention is to provide new and improved bondingmeans adapted for affording satisfactory bonds between members ofvarious and wide Idegrees of `differences in coelicients of expansion.

Another object of my invention is to provide new and improved bondingmeans adapted to be formed in such -a manner ras to facilitate thehandling thereof and to facilitate the adaption thereof to the bondingof members of various congur-ations.

Further objects and advantages of my invention will become 4apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed o ut with particularity in theclaims annexed to and forming part of this speciiication.

In carrying out the objects of my invention 4I provide an admixture of avitreous bonding material and metal particles between the members to bebonded. Then I inductively heat :the metal particles sufficiently tofuse the bonding material thereby to eliect the bond. The admixture ofbonding material and metal particles can be suitably bound and formedinto bonding members to be disposed between members to be joined or itcan be formed integral with one or more of the members to be joined.Additionally, the proportions of the ingredients of the admixture can bevaried to provide an admixture of substantially any desired coeicient ofexpansion for matching the expansion characteristics ofthe members toybe joined; and a plurality of layers of admixtures of progressivelysubstantially different coefficients of expansion can be provided tofacilitate bonding of members of substantially widely difterentcoeicients of expansion.

For a bet-ter understanding of my invention reference may be had .to theaccompanying drawing in which:

FIG. l is an enlarged side elevational View of an electronic tubepartially sectionalized to illustrate my invention applied to thebonding of the bulb and stem portions thereof;-

FIG. V2 is an enlarged perspective view of a bonding member made inaccordance with the teachings of my invention;

FIG. 3 is an enlarged fragmentary sectional view illustrating a modiedform of my invention;

FIG. 4 is an enlarged sectional view illustrating a manner of forming amember to be bonded with an lembodiment of my invention integrallylincorporated therein;

FIG. 5 is an enlarged fragmentary sectional view illustrating the mannerin which a member formed in accordance with FIG. 4 is adapted foreffecting a bond with another member; and

iFIG. 6 is an enlarged fragmentary sectional view illustrating stillanother modified yform of my invention.

Referring to FIG. 1, I have shown my invention applied to the bonding ofglass component parts of an electronic tube envelope 1. However, it isto be understood that my invention is not limited to the bonding orsealing of glass members of `an electronic tube or other similar device,but is equally applicable -to the bonding of all types of members ofmaterials such as metal, ceramic, etc. and that the members joined maybe "of different materials such as glass and metal, ceramic and metal,etc.

The tube envelope 1 comprises a glass bottle or bulb portion 2 and aglass stem 3. The bottle 2 is adapted for being bonded or `sealed at theedge 4 thereof to an edge'portion 5' of the stem 3. The stem 3 is formedto include leads or pins 6 embedded in and extending through the glassportion thereof, in the manner shown, Ato providefor electricalconnection to components of a tube cage (not shown) adapted for beingsealed in the envelope 1.

In order to bond the edge 4 of the bottle to the edge 5 of the stem, Ihave provided a bonding member 7. To conform to the cross-sectionalconfiguration of the envelope, the member 7 is shown formed as anannulus. However, it will be clear that in general, its conguration willdepend solely upon the configurations of the members to be joined orbonded. In an operative embodiment, in sealing a standard miniature tubetype, the member 7 was formed of a compressed admixture of a vitreousbonding material such as a glass frit of about -100 mesh, and a metalpower of approximately -325 mesh. By way of example, the metal powderwas composed of l percent copper, 10 percent molybdenum and 89 percentiron byy weight. Also by way of example, the

member 7 constituted `approximately 80 percent metal powder plus 20percent glass frit by weight.

The `member 7 may be formed by placing the admixture of glass and metalpowders in any suitable die or mold and thereafter administeringsuitable pressure to bind the materials together. Additionally, themember 7 may be sintered in a hydrogen atmosphere lfurnace at asuiciently high temperature and for an adequate period, such as atemperature of lapproximately 700 C. Ifor about 20 minutes, thereby tobind the materials together for further facilitating the handling and toreduce any reactions of the glass used with the atmosphere. Y Y

Alternatively, the frit Iand metal powder can be held together or boundto form the member 7 by means of .parat-lin or -any similar bindingmaterial which can subsequently be burned out as by inductive 4orfurnace heating of the metal panticles or powder for thus leaving themember in `a semi-sintered state.

Following formation of the bonding member 7 in either of theabove-described manners, the member 7 is placed on the portion 5 of thetube stem 3` in the manner shown in FIG. 1 and the bottle Z is placedover the 'tube cage (not shown) and vin good contact with the member 7in the manner #also shown in FIG. 1. Thereafter, the assembly is placedin a radio frequency field as by being insented in an energizedinduction coil designated 8. As

seen in the drawing, the assembly is so disposed in the coil 8 `as tosubject rthe member 7 to the lgreatest possible effect thereof. Thus,the metal portion of the member 7, comprising the metal particles orpowder, serves as an inductor in the radio frequency field for absorbingheat energy to melt the glass portion of the member 7, comprising theglass frit, and for transmitting heat to the edge 4 of the bottle 2 andthe edge 5 of the stern 3. As a result the melted frit Wets the edges tobe bonded and fuses therewith to effect a strong adherent bond betweenthe bottle and the stem thereby to form the assembly 1.

The strength of the joint or bond effected in the abovedescribed manneris enhanced by a keying or locking mechanism at and below lthe surfacesof the member 7. That is, the metal particles or powder dispersed in thematerial comprising the bond become keyed to the material at the edges 4and 5 of the bottle 'and stern, respectively, whereby the bond betweenthese members is strengthened.

It is to be understood that my invention is not limited to theparticular metal powders and percentages thereof referred to above, andcan be made of any combination of metal powders that :are compatiblewith each other and that when admixed with the glass frit will provide abonding member having the coefficient of expansion desired. That is, inaccordance with the coefficients of expansion of the members to bejoined, such as the bottle 2 and the stem 3, the particular met-alpowders and percentages thereof employed -in making up the member 7 maybe selected to provide a member having a coeicient of expansion adaptedfor substantially matching those of both of the members to be sealed.

Where members of widely different coellicients of expansion are to bebonded a plurality of bonding members such as the member 7, each with asubstantially different coefficient of expansion, may be employed in themanner shown in FIG. 3. That is, if members such as a A expansionsubstantially the same as the stem 3 could be placed on the edge 5 ofthe stem in the manner shown.

Thereafter, a member 9 formed in the same manner as the member 7 but ofingredients adapted for providing it with a coelicient of expansionsubstantially the same as the member 7 but somewhat closer to that ofthe bottle 2 may be placed on the member 7. I-f the coefficient ofexpansion of the member 9 does not substantially match that of thebottle 2, then still another member 10 formed of ingredients adapted`for substantially matching the coeicients of expansion of the member 9`and the bottle Z may be provided between the member 9 land the edge 4of the bottle in the manner shown in FIG. 3. Thus, it will be seen thatby providing a plurality of bonding members formed in accordance with myinvention and to provide progressively different coefficients ofexpansion it is possible to provide a bonding structure adapted foreffecting satisfactory seals between members of substantially widelydifferent coeicients of expansion. As seen in FIG. 3 the `assemblyprovidedin the just-described manner may be subjected to a radiofrequency eld provided by an induction coil 8. Thus, the metal portionsof the several bonding members made up of the metal particles or powdersthereof are adapted for absorbing energy thereby fto melt the glass ofthe various bonding members -and to heat the edges of the members to bebonded; and, in the same manner as described above with regard to FIG.1, a bond or seal is effected between the members 2 and 3. Y

It will be seen that while I have shown three bonding members 7, 9 and10 provided for effecting a bond between members of substantially widelydifferent coeicients of expansion, `any number thereof may be employedland the number used will be controlled only by the extent of thedifference of expansion characteristics of the members to be joined.

As seen in FIG. 4, the layer of an admixture of a vitreous 4bondingmaterial 'and met-al particles adapted for effecting a bond by means ofinductive heating needinot be separately formed as a bonding member suchas the annulus 7 and placed between the members to be bonded but may beformed integrally with one of these members. For instance, such a layermay :be formed as part of the edge 5 of the stem 3 which consists of thesteps of providing a suitable mold or die 1'1 adapted `for being lledwith powdered glass 12 and for holding in position the leads 6 to beembedded in the stem. Upon positioning of a suitable pressure plate 13over the prong portions of the leads 6 and exertion of an adequatepressure theref on the powdered glass 12 is caused to be compressed intoa single member comprising the stem 3. Now as seen in FIG. 4, thismethod readily lends itself to the formation of the bonding meansintegrally with the stem 3. This may be accomplished by placing anadmxture of vitreous bonding material and metal powder such as that usedin forming the member 7 on a shoulder 14 formed in the die 11 before allthe powdered glass 12 is deposited in the die. Thus when the stem 3 iscompletely formed by operation of the die structure in the mannerdescribed above `a bonding surface or structure designated 15 in FIGS. 4and 5 is for-med which is integra-l with the stem 3. With the bondingstructure 15 integral with one of the members to be bonded the othermember is simply placed into contact with the portion 15 in the mannershown in FIG. 5 and lthereafter the assembly is disposed in a radiofrequency field as by insertionf into the induction coil 8. As in theabove-described forms of my invention the metal particles in the bondingmeans 15 will absorb energy for heating up and thereby melting the glassfrit included in the bonding means 15 Iand for transmitting heat to theedges of the members to be bonded thereby to effect :a satisfactory andunusually strong bond.

Now with reference to FIG. 6, it will be seen that the just-describedform of my invention including the bond ing portion 15 formed integralwith the stem 3 and comprising an admixture of vitreous bonding materialand metal particles or powder may be employed `in cooperation with abonding member such as 7 to effect a bond between the bottle 2 and thestem 3. In this form of my invention the vitreous material included inthe portion 15 of the stem and that of the member 7 may be fused foreffecting a seal between the members to be joined and by means of thesame method described above. Specifically, the member 7 may be placed onthe stem 3 over the portion 15 and the bottle 2 may thereafter be placedin engagement with the member 7, and the whole assembly subsequentlyinserted into the energized induction coil 8. Upon sufficient subjectionof the assembly to the effects of the coil, the metal particles orpowder included in the portion 15 and the member 7 are caused to beinductively heated suiciently for `fusing the vitreous bonding materialor glass frit included in the portion 15 and the member 7 land heatingthe edges of the members to be bonded for thereby effecting asatisfactory seal.

It will be seen that when desired, such as. when the members to bejoined al'e of substantially widely different expansion charactersitics,-a lplurality of bonding members of progressively different coefficientsof expansion, such las those illustrated in FIG. 3, could be employed incombination with the integral bonding means 15 illustrated in FIGS. 5and 6.

It is to be understood that while I have shown the members 7, 9 and 10as vbeing separately formed they could alternatively be formed'as asingle member. That is, various admixtures of vitreous bonding materialand metal powders, each having a different coeicient of expansion, couldbe provided in the manner described above. Then, these admixtures couldbe spread in layers in la mold, with for example, the admixture ofsmallest coefficient at the bottom and ranging upwardly to that of thehighest y'coelicient Thereafter they could be pressed to form a singlebonding member and sintered in the man- Y that various modifications mayyet be devised by those Y skilled in the art which will embody theprinciples of the invention and found in the true spirit and scopethereof. What I claim as new and desire to secure by Letters Patent ofthe United States is:

1. A bonding member adapted for being positioned between elements to bebonded and for being heated inductively to a Ibonding 'temperaturecomprising an annular sintered metallic-matrix wholly formed of only asubstantially uniform adrnixture of approximately 80 percent metalparticles and 20 percent powdered glass by weight ofthe composition ofthe member.'

2. A bonding material adapted for being heated inductively to provide .avitreous seal betweenumembers to be joined-comprising a uniformadmixture of approximately 20% glass fr-it Iand 80% metal powder byweight, and said` metal powder being composed of `approximately 1percent copper, 10 percent molybdenum, and'89rpercent iron by weight.

3. A bondingV member adapted for being positioned between elements toVbe joined by a vitreous bond and for i being heated inductively to -atemperature for electing the bond comprising an annular sinteredmetallic matrix wholly formed of compressed metal particles and glassfrit with said glass frit uniformly dispersed between said metallparticles throughout said matrix, said metal particles constitutingapproximately 80 percent by weight of said matrix, said metal particlesbeing composed of approximately 1 percent copper, 10 percent molybdenum,

and 89 percent iron by weight, and said glass frit cont 6 stitutingapproximately 20 percent of said matrix for thereby providing la iuidglass surface on said matrix when said matrix is inductively heated tosaid temperature for effecting said bond. 4. A closure member for use insealing an end ofla glass envelope comprising a disc-like glass bodyincluding an integral annular rim portion on the surface of said lbody'and for being engaged by the end of said envelope, only said integralannular rim portion of said body having metal particles uniformlydistributed therein for being heated inductively to eiect flowing of theglass portion of said body at -said rim portion and heating of the endof an envelope engaging said portion, thereby to eiect -a vitreous s ealbetween said closure member and envelope end, and said metal particlescomprising approximately by weight of the composition of said annularrim portion of said glass body.

5. A member comprising an annular portion adapted for being heatedinductively -to a bonding temperature Y:for eie'cting a bond betweensaid annular port-ion and `ancomposition of said annular portion.

References Cited in the file of this patentY Y UNITED STATES PATENTS Y1,972,463 Schlecht Sept. 4, 2,246,165 Dawihl et ral., June 17, 19412,263,520 Romp .Nov. 18, 1941 2,415,036 Quinn Jan. 28, 1947 2,556,059-Braunsdori June 5, 1951 2,559,572 Stalego July 3, 1951 r2,654,822 Agulee Oct. 6, 1953 2,657,298 Andrus Oct. 27,' 1953 ,2,664,618 Kleis Jan. 5,1954 2,679,568 Smith et al. May 25, 1954 2,691,814 Tait Oct. 19, 19542,739,829 Pedlo'w et al. Mar. 27, 1956 2,771,969 -Brownlow Nov. 27,"1956Weiss ..-'Dec. 17, 1957.

1. A BONDING MEMBER ADAPTED FOR BEING POSITIONED BETWEEN ELEMENTS TO BEBONDED AND FOR BEING HEATED INDUCTIVELY TO A BONDING TEMPERATURECOMPRISING AN ANNULAR SINTERED METALLIC MATRIX WHOLLY FORMED OF ONLY ASUBSTANTIALLY UNIFORM ADMIXTURE OF APPROXIMATELY 80